Cytoskeletal structure of diseased and normal hemocytes of Mya arenaria

Abstract

Molluscan hemocytes function in the overall defense of the animal by phagocytosing foreign material. When this phagocytic ability is impaired the animal becomes increasingly vulnerable to physiological disruption by foreign agents. As in other bivalves, hemocytes of Mya arenaria have been shown to phagocytose a variety of foreign materials and to possess the hydrolytic enzymes necessary to degrade incorporate substances. However, hemocytes from diseased animals demonstrate almost no phagocytic capabilities. When allowed to settle on glass, diseased (abnormal) hemocytes remain rounded and generally unattached, with only a few short membrane extensions; they do not clump. Whole cell transmission electron microscopy preparations demonstrate an altered cytoskeletal architecture in diseased hemocytes as compared to that found in nondiseased (normal) cells. Hemocyte preparations incubated in rhodamine-conjugated phalloidin and observed with fluorescence microscopy show altered actin filament patterns in diseased hemocytes. The disrupted cytoskeletal structure observed in diseased hemocytes likely accounts for the inability of cells to clump, adhere to glass, and phagocytose foreign materials.